The present invention relates to sewing apparatus and, more particularly, to sewing machines of the type adapted to quilting.
The first practical sewing machine was independently invented by three different inventors in the United States in the period from the mid 1830's to 1850. The basic invention consisted of a reciprocating needle having an eye near its point and a reciprocating shuttle containing a bobbin of thread. As the threaded needle passed through to the opposite side of the cloth being sewn carrying the thread with it, the shuttle passes through a loop of thread formed on the underside of the cloth to loop the thread from its bobbin about the thread from the needle. Thereupon, the needle is withdrawn and the excess thread is drawn upward through the cloth to form a lock stitch.
The above basic invention appears to have been invented about 1830 by a Walter Hunt who, concerned about the possiblity that seamstresses would be thrown out of work, suppressed the invention and never applied for a patent. Elias Howe appears to have been the next rediscoverer of the invention about 1843 and received a patent on his invention in 1846. Isaac M. Singer was the third discoverer of the basic invention and received a patent on it in 1851.
Through the remainder of the 1800's and the first half of the 1900's, the basic sewing machine remained essentially unchanged with millions of units being produced for home and factory use worldwide.
More recently, the reciprocating shuttle has been virtually replaced in conventional sewing machines by a round bobbin. The round bobbin is much superior in efficiency, reliability and cost to the conventional shuttle.
A class of sewing machine to which the round bobbin has not been applied is the class of quilting machines. Quilting machines conventionally have two or more rows of needles which are reciprocated up and down together while the fabric is moved to form decorative patterns. A conventional quilting machine has a spacing between adjacent needles in a row of about one inch and a spacing between rows of about three inches. Quilting machines have employed pairs of shuttles to service one corresponding needle in each of the rows. In a quilting machine having, for example, 100 needles in a row, 100 pairs of shuttles have been reciprocated in correct phase with the operation of the needles.
From the above description of quilting machines, one can sense the extreme crowding of apparatus below the needle plate in order to form as many as 200 stitches at the same time. Due to the large number of simultaneous operations, the added smoothness, reliability and reduced cost of round bobbins would be desirable. However, due to the restricted space available in quilting machines, the use of round bobbins has not been successfully applied. Thus, present quilting machines require a large number of parts such as, for example, 1,040 parts not counting screws in a 72" wide standard quilting machine. A significant portion of these parts are special complicated expensive castings. With so many parts operating in a typical start-and-stop fashion of reciprocating shuttles, high complexity leading to high manufacturing and maintenance cost results.
From the standpoint of production, an uninterrupted run of a quilting machine is limited largely by the capacity of the bobbins in the shuttles. If a relatively small bobbin is employed, a relatively short run time of two or three hours is possible before the bobbins in all of the shuttles must be replenished. Although it is possible to use larger bobbins in the shuttles, when this is done, the machine must be slowed down due to the increased inertia of the many larger shuttles and bobbins.